Having problems with add-ons: missing add-ons and incorrect warnings?
The reason it doesn't show up is that the "Add Curve" part of the name of the addon is simply the category in which it is located. If you search the rest of the name "Extra Objects" it will show up.

As far as I know, the warnings for needing other settings show up whether they are necessary or not. Not necessarily a bug, but it could be improved in the future to disappear if everything is in order.